Set up your grill for low, even heat. If using a charcoal grill, distribute the coals evenly. If using a gas grill, heat both sides.
Slowly heat the milk/cream over low heat to 86 degrees F. Remove from the heat. Mix in the starter packet, mixing for no more than 15 seconds. Allow to sit at room temperature for at least 12 hours.
The next day: Ladle the solids into a cheesecloth-lined strainer set over a mixing bowl. Gather up the cheesecloth to cover the surface and refrigerate overnight, allowing the cheese to drain and firm up.
The next day, pick up the cheesecloth and pour the cream cheese into a mixing bowl. Season with salt and stir to combine. (If you’d like a firmer cheese, continue to press.)